Propane or diesel powered heater with common burner opening

ABSTRACT

A coolant heater having a coolant tank and a burner tube within the coolant tank is used for marine and motor coach installations and is used for either a liquid powered or gas powered burner.

INTRODUCTION

This invention relates to a heater and, more particularly, to a heater used primarily in recreational vehicles and boats and which allows the burner opening within the coolant tank to be used for either a diesel or propane fuel burner.

BACKGROUND OF THE INVENTION

Recreational vehicles, motor homes, trucks, boats and the like, particularly those of the larger variety, often have a plurality of water and coolant circuits. A first circuit may extend from the engine of the vehicle or boat and is typically used for heating the interior or the vehicle or boat. A second circuit may extend from an auxiliary heater which may also be used for heating when the engine is not operating. A third circuit may extend from a source of potable water used for cooking and other personal use. To assist in the significant movement of coolant and potable water, it may be required to use two or more heaters or additional pumps to supply the necessary thermal energy for the heating and also for fluid movement. Of assistance to the flexibility of the system is the distribution module disclosed in our United States patent application serial no. 20050284948 entitled DISTRIBUTION MODULE FOR WATER HEATER filed Dec. 29, 2005, the contents of which are incorporated herein by reference.

For smaller motor coaches and smaller boats, the use of a distribution module and externally located pumps may be unnecessary. In such event, it would be useful to have the burner, the various pumps, the heat exchanger, the expansion tank and the overflow bottle in a single location within a single heater casing. The casing would conveniently be relatively small to take advantage of the reduced space available on a smaller motor coach or a smaller boat.

Heretofore, the exhaust manifold connected to the burner tube has been designed for operation atop the coolant tank. The heater, being used for both RV and for marine use, conveniently requires an exhaust manifold which will allow an exhaust duct to exit the exhaust manifold in an “up” configuration for marine installations and a “down” configuration for RV installations. The exhaust manifold, therefore, was designed to extend beyond the end of the burner tube within the coolant tank so that the exhaust manifold could have either an up or down type exhaust configuration without modifying the coolant tank. This required more space within the coolant tank which was unnecessary and undesirable.

A further disadvantage with existing systems is that the burner tube is generally located in the center of the coolant tank or at least on the vertical plane defining the center of the coolant tank. The heater heats the coolant fluid unevenly because of the conflicting directions of flow of the heated coolant and there may be zones of coolant at different temperatures within the coolant tank. This affects efficient operation of the heater where precise coolant temperatures and predictable fluid flow are desirable.

Yet a further disadvantage of existing systems is the use of a pump which is connected directly to the expansion tank which receives coolant from or provides coolant to the coolant tank. A level switch is typically positioned within the coolant tank and when the coolant is low, the level switch terminates operation of the heater. By this time, however, the expansion tank may be empty and the pump thereafter runs dry before terminating operation. Air is introduced into the fluid lines which is not desirable and is inconvenient.

If a heater is ordered by a user for use in a propane fueled version as compared to a diesel type version and vice versa, it is disadvantageous to use two different heater configurations. It would be useful to have as many common components as possible to avoid unique heater configurations for each fuel.

SUMMARY OF THE INVENTION

According to the invention, there is provided a heater system comprising a heater having a burner tube which is adapted to receive a burner, said burner tube being positioned within said heater, said burner tube being positioned so as to heat the coolant within a tank of said heater, said burner tube being capable of carrying either a a gas or liquid fuelled burner, said outside diameter of said burner being similar to the inside diameter of said burner tube.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Specific embodiments of the invention will now be described, by way of example only, with the use of drawings in which:

FIG. 1 is a diagrammatic schematic side view of the heater within the heater casing;

FIG. 2 is a diagrammatic partial plan view of the heater casing particularly illustrating the coolant tank and the exhaust manifold within the heater casing; and

FIG. 3 is a partial diagrammatic view of the coolant tank illustrating the opening for the burner tube and the sidewise location of the exhaust manifold and exhaust pipe; and

FIG. 4 is a block diagram illustrating the operating components of a propane burner.

DESCRIPTION OF SPECIFIC EMBODIMENT

Referring now to the drawings, a coolant heater is generally illustrated at 100. It includes a heater casing 101 housing most of the components of the coolant heater 100. Such components include the burner 102, the burner tube 103 and the exhaust manifold 104 (FIG. 2 which is connected to the burner tube 103 by passageway 110 (FIG. 3). An electric element 105 is also mounted within the coolant tank 111 and is used for coolant heating when a shore connection or an RV connection is available for obtaining power. The burner tube 103, the exhaust manifold 104 and the passageway 110 are all positioned within a coolant tank 111 which contains coolant and which coolant is circulated through a heat exchanger 112 and coolant and potable water circuits under the influence of a pump 132 as will be described.

The burner tube 103 has a longitudinal axis 113 which runs generally horizontally within the heater casing 101 as best seen in FIGS. 1 and 3. The coolant tank 111 similarly has a longitudinal axis 114 (FIGS. 2 and 3) which runs generally horizontally within the heater casing 101. The longitudinal axis 113 of the burner tube 103 is offset from the longitudinal axis 114 of the coolant tank 111 a distance “d” (FIG. 2). This allows substantial room to be left adjacent the burner tube 103 within the coolant tank 111 and such room is used to position the exhaust manifold 104 within the coolant tank 111 with the connecting passageway 110 extending from the burner tube 103 to the exhaust manifold 104.

In heaters used within recreational vehicles, it is generally preferable to have an exhaust duct 120 extending downwardly from the exhaust manifold 104 so that it will extend through and beneath the floor of the recreational vehicle to exhaust the combustion fumes beneath the motor home. If the coolant heater 100 is being used within a boat, it is generally preferable to have the exhaust duct 120 extending upwardly from the exhaust manifold 104 so that the exhaust duct 120 can conveniently terminate in the transom of the boat within which it is installed as is illustrated in FIGS. 2 and 3. Both such configurations are easily obtained using the position of the offset burner tube 103 as has been described without the requirement for extending the exhaust manifold 104 beyond the end of the burner tube 103 which would otherwise require a larger coolant tank 111.

The expansion tank 121 is connected to the coolant tank 111 by way of coolant hose 122. The expansion tank 121 functions to receive coolant from and to supply coolant to the coolant tank 103 caused by expansion and contraction of the fluid during operation of the heater 100. The level of coolant within expansion tank 121 corresponds generally with the level of coolant within the coolant tank 103. A level switch 123 is positioned within the expansion tank 121 so that if the level of coolant in expansion tank 121 drops below a predetermined quantity, the operation of the burner 102 will terminate. A pressure cap 124 is mounted on the top of expansion tank 121 and extends from the heater casing 101. If the pressure within expansion tank 121 exceeds a predetermined quantity, conveniently seven (7) psi for a diesel fueled heater known as the HURRICANE (Trademark) heater manufactured by International Thermal Research Ltd. of Richmond, British Columbia, Canada, the pressure cap 124 will allow the coolant to pass to an overflow bottle 130 through duct 131. If the pressure within expansion tank 121 drops below zero psi, the coolant will return to the expansion tank 121.

The bottom of expansion tank 121 exits to circulation pump 132 which pumps the coolant from the expansion tank 121 to heat exchanger 112 and thence to the remainder of the hydronic coolant loop 133 which exits from the heater exchanger 112. One loop 134 extends from the heater casing 101 to radiators or fans 135 where the heated coolant is used for space heating within the boat or coach. The heated coolant then returns to the coolant tank 111 through a three-way valve 140. If the coach or boat is being heated, the three-way valve 140 will be in the open position to allow such circulation of heated coolant through loop 134. If, however, there is no heating required such as in the summer months, the three-way valve 140 is manually closed thus preventing flow through loop 134 and allowing the coolant from heat exchanger 112 to return directly to coolant tank 111 through coolant hose 141.

A potable water heating loop 142 extends from the heat exchanger 112. The loop 142 enters a mixing valve 143 located outside the heater casing 101 for ready accessibility. The heated potable water from the heat exchanger 112 mixes with cool water entering the mixing valve 143 at inlet 144. The mixing valve 143 sets the temperature of the heated potable water which exits the mixing valve 143 at outlet 150 and flows into a potable water loop 151 which may service taps, showers and the like as is illustrated diagrammatically at 55. The cool potable water enters the heat exchanger 112 and mixing valve 143 from line 152 which extends from the source of potable water, conveniently an onboard water tank or a service line connected to a municipal water supply if the boat or motor coach has such a supply available.

Operation

The coolant heater 100 is compact in size in order to install the heater 100 is spaces of reduced dimensions. One way the heater 100 is reduced in size is to have the burner tube 103 offset sidewise from the axis 114 of the coolant tank 111. Likewise and to reduce the space required for the heater 100, the major operating components of the coolant heater 100 including the coolant tank 111, the burner tube 103, the exhaust manifold 104, the overflow bottle 130, the expansion tank 121, the circulation pump 132, the heat exchanger 112, the electric element 105 and the three-way valve 140 are all positioned within the heater casing 101.

In operation, cool potable water will be supplied through potable water line 152 to the heat exchanger 112 and to the mixing valve 143. It will be assumed that there is sufficient coolant within the coolant tank 111 to service the space heating loop 134 and that such coolant is also of a depth within the expansion tank 121 to allow the level switch 123 to indicate safe operation of the burner 102.

The burner 102 will commence operation under the influence of a thermostat or other control (not shown) and the coolant within the coolant tank 111 will be heated. Because of the offset location of the burner tube 103 within the coolant tank 111, the heated burner tube 103 will set the coolant in motion due to the uneven heating of the coolant. This coolant motion will more uniformly distribute the temperature of the coolant throughout the coolant tank 111. The exhaust from the combustion within the burner tube 103 will flow through passageway 110 to the exhaust manifold 104. The exhaust will exit the exhaust manifold 104 either from an “up” configuration as is illustrated in FIGS. 2 and 3 and as is used within a boat or from a “down” configuration as illustrated in FIG. 1 in which the exhaust will exit the exhaust manifold 104 downwardly.

The pump 132 connected to the expansion tank 121 which holds coolant in addition to that coolant in coolant tank 111 will commence operation when the coolant reaches a desired temperature under the influence of a coolant temperature transducer (not shown) and the coolant will thereby be pumped from the expansion tank 121 through heat exchanger 112 and out hydronic loop line 133. If the three-way valve 140 is open, the coolant will be displaced through space heating loop 134 to fans 135 where space heating within the coach or boat will occur and where, thereafter, the coolant will return to the coolant tank 111 through the three-way valve 140. If the three-way valve 140 is closed, the coolant in line 133 will return directly to the coolant tank 111 through line 141 and three-way valve 140 without passing through the space heating loop 134.

The potable water supply (not shown) is supplying cool potable water to the heat exchanger 112 and to the mixing valve 143 through line 152. The cool water will be heated within the heat exchanger 112 and will pass to the mixing valve 143 where adjustment of the mixing valve 143 will set the outlet water temperature which potable water is then passed to the heated potable water loop 151 at the desired temperature.

In the event there is a coolant leak or if another event causes the level switch 123 to close, thereby indicating a lack of coolant in the expansion tank 121, a control board (not shown) will immediately shut down the burner 102 to prevent any overheating or other damage caused by low coolant. The pump 132 will remain running until the coolant within the coolant tank 111 cools to a predetermined temperature. Since the level switch 123 is within the expansion tank, the heater terminates operation while fluid is still in the tank 121. This prevents the pump 132 from running dry which would require inconvenient air purging of the coolant system.

In the event the pressure within expansion tank 121 exceeds a predetermined level, conveniently seven (7) psi, the pressure cap 124 will open thereby allowing coolant to escape from the expansion tank 121 to the overflow bottle 130. When the coolant cools, the pressure within the expansion tank 121 will reduce and coolant will be returned through negative pressure to the expansion tank 130.

Many modifications are readily contemplated. For example, mixing valve 143 may be manually or automatically adjusted and likewise for three-way valve 140.

It is further contemplated according to a further aspect of the invention, that the heater 100 may be powered by either a liquid or gaseous fuel. To that end, it is desirable to avoid the significant design and component costs which would be necessary if each different burner required a custom produced heater to accommodate the burner. Reference is made to FIG. 4 where a propane supply 201 is connected to an operating valve 202 which terminates or commences the flow of gas 201 to the propane fuel nozzle 203. The fuel nozzle 203 is adapted to fit within the burner tube 103 of FIG. 1. Thus, the operating components required by the diesel fueled burner 102 (FIG. 1) are deleted in the propane fueled version of FIG. 4 and the propane nozzle 203 together with its associated operating components, namely the valve 202 and propane supply 201 are used instead. The outside diameter of the burner tube 103 remains identical to the outside diameter of the burner tube 103 of the diesel fueled configuration in order to avoid unnecessary production costs with two different fueled versions.

Many further modifications will readily occur to those skilled in the art to which the invention relates and the particular embodiments described are given by way of example only and are not intended as limiting the scope of the invention as defined in accordance with the accompanying claims. 

1. A heater system comprising a heater having a burner tube which is adapted to receive a burner, said burner tube being positioned within said heater, said burner tube being positioned so as to heat the liquid within a tank of said heater, said burner tube being operable to carry either a gas or liquid fuelled burner, said outside diameter of each of said burners being similar to the inside diameter of said burner tube. 